1. Field of the Invention
The present invention generally relates to an electrophotographic process and, more particularly, to an image forming method and a device therefor designed to reproduce a multi-colored image by the use of the electrophotographic process.
2. Description of the Prior Art
With increase in number of available functions in a copying machine and also with increased applications thereof, the availability is expected of a copying machine capable of making a copy of a multi-colored image corresponding in color to the multi-colored original document. However, the copying machine currently available in the market is generally of a type capable of making copies on monochromatic basis.
Accordingly, if attempt is made to make this kind of image forming machine capable o making multi-colored copies, the machine has to be equipped with a number of developing units equal to the number of colors desired to be reproduced and, at the same time, the machine is required to have a capability of transferring and fixing a corresponding number of powder images onto one and the same copying sheet.
However, when it comes to the copying machine having a resolution of reproducing seven to eight colors, rather than two to three colors, the space in the machine occupied by the plural developing units will be considerably increased and, accordingly, not only the latent image carrier, but also the machine itself will become considerably bulky and expensive. Also, since the copying sheet is thermally affected each time it is passed through a fixing unit, the copying sheet when passed through the fixing unit several times will be curled to such an extent as to result in a displaced reproduction of the image on the copying sheet.
Also, in a multi-color development, a problem associated with color distortion tends to occur when a color reproduction is attempted with the use of two or more kinds of toner material. Although this problem will not be noticeable if combined with yellow, a combination of magenta and cyan tends to result in the noticeable color distortion.